Discontinuous sets of knee extensions induce higher cardiovascular responses in comparison to continuous ones

Background. The strength training can promote significant cardiovascular responses (luring its performance and it is interesting to devise strategies to reduce them, without compromising the strength production. Objective: To compare the acute cardiovascular responses of systolic arterial pressure (SAP), diastolic arterial pressure (DAP), heart rate (HR) and double product (DP) during the unilateral knee extension (four series of 8 maximum repetitions) performed continuously or discontinuously. Both protocols involved a 2-minute interval between the series and the discontinuous protocol had an extra interval of 2 seconds between the 4(th) and the 5(th) repetitions. Methods: Eight healthy men trained in muscular strength (aged 26 6 years) participated in the data collection and were randomly divided in two non-consecutive days. The cardiovascular responses were measured by photoplethysmography (Finapres, Ohmeda, Louisville, CO US, V at rest, at the end of each series and 2 minutes after the performance of each protocol. Results: The discontinuous series showed significantly higher values when compared to the protocol of the continuous series for: SAP (mmHg) at the 2(nd) (73.1 +/- 5.4 vs 1520 +/- 4.0; p=0.001), 3(rd) (188.9 +/- 8.6 v.s 162.4 +/- 6.0; p=0.000) and 4(th) series (793.1 +/- 8.1 vs 161.6 +/- 5.9; p=0.000); DAP (mmHg) at the 3(rd) (103.8 +/- 4.1 vs 86.7 +/- 3.3; p=0.000) and 4(th) series (104.1 +/- 2.7 vs 83.4 +/- 3.3; p=0.000); DP (mmHg.bpm) at the 2(nd) (17,907.5 +/- 1,350.7 vs 14,541.9 +/- 1,848.0; p=0.03), 3(rd) (19,687.3 +/- 1,444.3 vs 15,612.1 +/- 1,180.3;p=0.008) and 4(th) series (21,271 +/- 1,794.2 vs 15,992.0 +/- 1,093.4; p=0.001). Conclusion: The discontinuous protocol promoted higher increase in pressure responses when compared to the continuous one. However, due to the characteristics of the study design, further studies are necessary to support these findings.